Extracellular Polymeric Substances Induced Porous Polyaniline for Enhanced Cr(VI) Removal from Wastewater

Abstract

Extracellular polymeric substances (EPS) of bacteria were used as templates for synthesizing unique polyaniline nanocomposites, i.e., porous EPS-modified polyaniline (EPS@PANI). The proteins were responsible for forming porous structure, while polysaccharides for the fiber morphology of EPS@PANI. The specific surface area (53.2 m2/g) of these unique EPS@PANI with an optimal EPS loading of 2 wt % was ∼2 times larger than that of pristine PANI. The PANI in EPS@PANI stayed as the emeraldine form and acted as the electron donor for reduction of Cr(VI) to Cr(III). Herein, 1.0 mg/L Cr(VI) was completely reduced to Cr(III) by 600 mg/L of EPS@PANI within 10 min, which was much faster than the pristine PANI (1 h). A maximum Cr(VI) removal capacity of 913.2 mg/g was achieved by these unique EPS@PANI nanocomposites and was ∼4.7 times higher than the pristine PANI (193.8 mg/g). Moreover, the isoelectric point (pI) was decreased from pH 7.5 for pure PANI to ∼4.5 for these porous EPS@PANI nanocomposites due to the low ...